U.S. patent number 7,463,933 [Application Number 10/870,211] was granted by the patent office on 2008-12-09 for lead retention means.
This patent grant is currently assigned to Medtronic, Inc.. Invention is credited to Jay A. Erlebacher, John L. Sommer, Dale A. Wahlstrom.
United States Patent |
7,463,933 |
Wahlstrom , et al. |
December 9, 2008 |
Lead retention means
Abstract
An elongate body of a medical device includes at least one
retaining segment extending along a length of the body, the
retaining segment including a plurality of fish-like scales
directed in a first common direction.
Inventors: |
Wahlstrom; Dale A. (Plymouth,
MN), Erlebacher; Jay A. (Tenafly, NJ), Sommer; John
L. (Coon Rapids, MN) |
Assignee: |
Medtronic, Inc. (Minneapolis,
MN)
|
Family
ID: |
34808507 |
Appl.
No.: |
10/870,211 |
Filed: |
June 17, 2004 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20050171588 A1 |
Aug 4, 2005 |
|
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
10771643 |
Feb 4, 2004 |
7212869 |
|
|
|
Current U.S.
Class: |
607/126 |
Current CPC
Class: |
A61N
1/057 (20130101); A61N 2001/0585 (20130101) |
Current International
Class: |
A61N
1/00 (20060101) |
Field of
Search: |
;607/116,118,126,128,130-131,122-123 ;600/373-375 ;606/72
;604/175 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Bockelman; Mark W
Attorney, Agent or Firm: Soldner; Michael C.
Parent Case Text
RELATED APPLICATION
This application is a continuation-in-part of application Ser. No.
10/771,643 filed on Feb. 4, 2004 and entitled "Novel Lead Retention
Means" which is now U.S. Pat. No. 7,212,869.
Claims
What is claimed is:
1. A medical lead, comprising: an elongate body having an
electrical conductor therein; a first retaining segment, extending
along a length of the body, forming a first fixed portion of an
outer surface of the body and including a first end and a first
plurality of projections extending in a first direction from the
first portion of the outer surface, each of the first plurality of
projections including a terminal edge directed toward the first
end; and a second retaining segment, longitudinally separate and
detached from the first retaining segment, extending along another
length of the body, forming a second fixed portion of the outer
surface of the body and including a second end opposite the first
end, and a second plurality of projections extending in a second
direction opposite the first direction from the second fixed
portion of the outer surface, each of the second plurality of
projections including a terminal edge directed toward the second
end; wherein the first plurality of projections and the second
plurality of projections are formed from a bioabsorbable material
and are adapted to interfere with a wall of a vessel to retain the
body within the vessel.
2. The medical lead of claim 1, wherein the first retaining segment
is positioned proximal to the second retaining segment.
3. The medical lead of claim 1, wherein the first retaining segment
and the second retaining segment each extend about an entire
circumference of the body.
4. The medical lead of claim 1, wherein the first retaining segment
and the second retaining segment each extend about a portion of a
circumference of the body.
5. The medical lead of claim 1, wherein the body includes an
elongate outer sheath and the first retaining segment and the
second retaining segment are each an integral part of the
sheath.
6. The medical lead of claim 1, wherein the first retaining segment
and the second retaining segment are formed on a collar positioned
about the body.
7. The medical lead of claim 1, further comprising a tubular
structure deployable over the first plurality of projections and
the second plurality of projections.
8. The medical lead of claim 1, wherein the body includes at least
one pre-formed curve in proximity to the first retaining segment
and the second retaining segment.
9. The medical lead of claim 1, wherein the first plurality of
projections and the second plurality of projections are
barb-like.
10. The medical lead of claim 1, wherein the first plurality of
projections and the second plurality of projections are fish
scale-like.
11. A medical lead, comprising: an elongate body having an
electrical conductor therein; a first retaining segment, extending
along a length of the body, forming a first fixed portion of an
outer surface of the body and including a first end and a first
plurality of projections extending from the first portion of the
outer surface, each of the first plurality of projections including
a terminal edge directed toward the first end; and a second
retaining segment, longitudinally separate and detached from the
first retaining segment, extending along another length of the
body, forming a second fixed portion of an outer surface of the
body and including a second end opposite the first end and a second
plurality of projections extending from the second fixed portion of
the outer surface, each of the second plurality of projections
including a terminal edge directed toward the second end, wherein
the first plurality of projections and the second plurality of
projections are adapted to interfere with a wall of a vessel to
retain the body within the vessel, the first retaining segment and
the second retaining segment are formed on a collar positioned
about the body, and the collar is formed from a bioabsorbable
material.
12. A medical lead, comprising: an elongate body having an
electrical conductor therein; a first retaining segment, extending
along a length of the body, forming a first fixed portion of an
outer surface of the body and including a first end and a first
plurality of projections extending from the first portion of the
outer surface, each of the first plurality of projections including
a terminal edge directed toward the first end; a second retaining
segment, longitudinally separate and detached from the first
retaining segment, extending along another length of the body,
forming a second fixed portion of an outer surface of the body and
including a second end opposite the first end and a second
plurality of projections extending from the second fixed portion of
the outer surface, each of the second plurality of projections
including a terminal edge directed toward the second end, wherein
the first plurality of projections and the second plurality of
projections are formed from a bioabsorbable material and are
adapted to interfere with a wall of a vessel to retain the body
within the vessel; and a dissolvable coating temporarily covering
the first plurality of projections and the second plurality of
projections.
13. A medical lead comprising an elongate body having an electrical
conductor therein; at least one retaining segment extending along a
length of the body, the retaining segment including a first
plurality of fish-like scales directed in a first common direction;
and a second retaining segment, longitudinally separate and
detached from the at least one retaining segment, extending along a
length of the body, the second retaining segment including a second
plurality of fish-like scales directed in a second common direction
opposite to the first common direction; wherein the first plurality
of fish-like scales and the second plurality of fish-like scales
are formed from a bioabsorbable material.
14. The medical lead of claim 13 wherein the first plurality of
fish-like scales and the second plurality of fish-like scales are
disposed in an overlapping pattern.
15. The medical lead of claim 13 wherein the first plurality of
fish-like scales and the second plurality of fish-like scales are
disposed in a plurality of circumferential rows and each individual
one of the plurality of circumferential rows of scales is disposed
in offset relation to an adjacent circumferential row of
scales.
16. The medical lead of claim 13 wherein the elongated body has at
least one preformed curved section in proximity to the retaining
segment.
17. The medical lead of claim 16 wherein the curved section is
disposed distally of the retaining segment.
18. The medical lead of claim 13 wherein the elongated body has a
serpentine shape along the length thereof.
19. The medical lead of claim 13 wherein the elongate body is sized
to move within a vessel and the retaining segment is characterized
in allowing movement of the elongate body within the vessel in the
common direction to an implanted position and preventing movement
of the elongate body from the implanted position in an opposite
direction to the common direction.
20. A medical lead comprising an elongate body; at least one
retaining segment extending along a length of the body, the
retaining segment including a first plurality of fish-like scales
directed in a first common direction; and a second retaining
segment, longitudinally separate and detached from the at least one
retaining segment, extending along a length of the body, the second
retaining segment including a second plurality of fish-like scales
directed in a second common direction, wherein the elongate body
includes a lead body having the retaining segment thereon, an
electrode at one end of the lead body, a connector at an opposite
end of the lead body from the electrode and a conductor
electrically coupling the electrode to the connector; wherein the
first plurality of fish-like scales and the second plurality of
fish-like scales are formed from a bioabsorbable material.
21. A medical lead comprising an elongate body having an electrical
conductor therein; at least one retaining segment extending along a
length of the body, the retaining segment including a first
plurality of fish-like scales directed in a first common direction;
and a second retaining segment, longitudinally separate and
detached from the at least one retaining segment, extending along a
length of the body, the second retaining segment including a second
plurality of fish-like scales directed in a second common
direction, wherein the elongated body has at least one preformed
curved section in proximity to the retaining segment, and wherein
the retaining segment is disposed in the curved section; wherein
the first plurality of fish-like scales and the second plurality of
fish-like scales are formed from a bioabsorbable material.
22. A medical lead comprising an elongate body having an electrical
conductor therein; at least one retaining segment extending along a
length of the body, the retaining segment including a first
plurality of fish-like scales directed in a first common direction;
a second retaining segment, longitudinally separate and detached
from the at least one retaining segment, extending along a length
of the body, the second retaining segment including a second
plurality of fish-like scales directed in a second common
direction; and a dissolvable coating disposed over the retaining
segment; wherein the first plurality of fish-like scales and the
second plurality of fish-like scales are formed from a
bioabsorbable material.
23. A medical lead comprising: an elongate body having an
electrical conductor therein; at least one retaining segment
extending along a length of the body, the retaining segment
including a first plurality of fish-like scales directed in a first
common direction; a second retaining segment, longitudinally
separate and detached from the at least one retaining segment,
extending along a length of the body, the second retaining segment
including a second plurality of fish-like scales directed in a
second common direction; and a thin-walled tube disposed in
concentric relation about the retaining segment; wherein the first
plurality of fish-like scales and the second plurality of fish-like
scales are formed from a bioabsorbable material.
Description
TECHNICAL FIELD
The present invention relates to medical devices and more
particularly to means for retaining or preventing dislodgement of a
lead positioned within a body.
BACKGROUND
Medical devices often include a therapy generator and one or more
elongate leads, coupled thereto, which are positioned within a
patient's body to deliver therapy from the generator. Such therapy
may be in the form of electrical stimulation, delivered via
electrical conductors extending through a lead body, or fluid
infusion, delivered via a lumen extending through a lead body. Some
examples of electrical stimulation include pacing and
defibrillation; some examples of fluids, which may be infused,
include drugs, nutrients, and genetic materials. In many
applications, leads are inserted through one or more blood vessels
and are ultimately positioned within a blood vessel where the lead
must be retained for a period of time in order to deliver the
therapy. Therefore it is desirable to provide lead retention means
allowing insertion or forward motion of lead, to position the lead
within a vessel, while preventing further forward motion and
rearward motion of the lead during subsequent therapy delivery.
BRIEF DESCRIPTION OF THE DRAWINGS
The following drawings are illustrative of particular embodiments
of the invention and therefore do not limit its scope, but are
presented to assist in providing a proper understanding of the
invention. The drawings are not to scale (unless so stated) and are
intended for use in conjunction with the explanations in the
following detailed description. The present invention will
hereinafter be described in conjunction with the appended drawings,
wherein like numerals denote like elements, and:
FIG. 1 is a plan view with a partial section of a lead including
means for retention according to one embodiment of the present
invention;
FIG. 2A is an enlarged plan view of a retention means according to
one embodiment of the present invention;
FIG. 2B is an enlarged partial section view of means for retention
according to an alternate embodiment;
FIG. 2C is an enlarged plan view of means for retention according
to another embodiment;
FIG. 2D is an enlarged partial section view of means for retention
according to yet another embodiment of the present invention;
FIG. 3 is a plan view of a lead which may incorporate retention
means according to embodiments of the present invention;
FIGS. 4A-B are plan views of a portion of a lead body including
retention means according to an alternate embodiment of the present
invention;
FIGS. 5A-B are schematic views of a portion of a lead body
including retention means according to yet another embodiment of
the present invention;
FIG. 6 is a schematic view of a medical device, which may
incorporate retention means according to embodiments of the present
invention; and
FIG. 7A-B are plan views of lead distal portions including
retention means according to additional embodiments of the present
invention.
DETAILED DESCRIPTION
The following detailed description is exemplary in nature and is
not intended to limit the scope, applicability, or configuration of
the invention in any way. Rather, the following description
provides a practical illustration for implementing exemplary
embodiments of the invention.
FIG. 1 is a plan view with a partial section of a lead 10 including
means for retention 15 according to one embodiment of the present
invention. FIG. 1 illustrates lead 10 including a lead body 12, a
connector 16 coupled to a proximal end 121 of the lead body 12 and
an electrode 14 coupled to a distal end 122 of the lead body 12; a
conductor 13, extending within an outer sheath 11, couples
electrode 14 to connector 16, in order to deliver electrical
stimulation, and forms a lumen for slideably engaging a stylet 18.
Means and materials for constructing such a lead are well known to
those skilled in the art.
FIG. 1 further illustrates retention means 15 formed along an outer
surface of lead body 12 in proximity to distal end 122. According
to embodiments of the present invention, retention means 15 allows
insertion of lead body 12 through a vessel, for example a vessel
607 as illustrated in FIG. 6, while preventing retraction of lead
body 12 within the vessel due to an interference of retention means
15 along a wall of the vessel that contacts lead body 12. Retention
means according to some embodiments of the present invention
extends along a length greater than or equal to approximately 1 mm
and may be implemented along any portion of a lead body alone or in
conjunction with other retention means; further, retention means 15
may be an integral part of outer sheath 11 or may be formed on a
separate collar fitted about lead body 12, either in-line with or
about outer sheath 11. Suitable materials for outer sheath 11 and
retention means 15 include those that are biocompatible, examples
of which include, but are not limited to, silicone and
polyurethane.
Various embodiments of retention means include projections formed
along retaining segments as illustrated in FIGS. 2A-D and 4A-5B. It
should be noted that alternate embodiments include, but are not
limited to, retaining segments extending around an entire
circumference of a lead body and segments extending only about a
portion of the circumference of the lead body. For example, a
plurality of projections may lie in a line, single file, along a
length of a retaining segment, as illustrated in FIG. 2A, or each
individual projection may extend circumferentially about all or a
portion of a retaining segment, as illustrated in FIG. 2C, or a
plurality of projections may lie approximately side-by-side about
all or a portion of a circumference, as illustrated in FIG. 2D.
In some embodiments, retaining segments as a whole or just the
projections may be formed of a bioabsorbable material, examples of
which include those taught in lines 10-24 of U.S. Pat. No.
6,173,206. According to these embodiments, if a lead body is
chronically implanted, the retaining segment or projections would
remain intact long enough to hold the body in place for a period of
time up to tissue encapsulation of the body; this may facilitate
extraction of a chronically implanted lead. One example of an
appropriate bioabsorbable material, polydioxanone is described
along with means for molding the material in U.S. Pat. No.
4,490,326, the teachings of which are incorporated by reference
herein.
FIG. 2A is an enlarged plan view of means for retention according
to one embodiment of the present invention. FIG. 2A illustrates a
retaining segment 380 including a plurality of barb-like
projections 385 positioned in a single-file line along a length of
the segment 380; each of the plurality of projections 385 include a
length L and extend laterally from a lead body 312 toward a
proximal end 321 at an angle 33, which, according to some
embodiments, is less than approximately 45 degrees. According to
this embodiment of the present invention and various other
embodiments illustrated herein length L is greater than
approximately 100 microns. FIG. 2A further illustrates projections
385 as portions of a wall 387 forming retaining segment, having
been lifted out of wall 387 according to one embodiment of the
present invention. FIG. 2B illustrates an alternate retaining
segment 30 extending along a length of lead body 312 and including
tread-like projections 31 extending laterally from lead body 312 to
form a textured surface adapted to engage a vessel wall, similar
to, for example, a sole of a shoe designed to facilitate traction.
According to some embodiments of the present invention,
projections, i.e. 385, 31, are directly formed in outer surfaces,
being integral with a bulk material underlying the surfaces, but,
according to alternate embodiments, the projections are formed of
separate materials either embedded in or adhered to these surfaces.
Alternative methods of forming examples of these embodiments will
be described herein below.
FIG. 2B further illustrates retaining segment 30 including a
coating 36, which is soluble in body fluids; according to this
embodiment, coating 36 fills in around projections 31 and remains
intact temporarily, during positioning of lead body 312, so that
lead body 312 may be moved back and forth through a vessel if
repositioning is necessary. Suitable materials forming coating 36
are soluble in body fluids (within a temperature range encompassing
normal body temperature), non-toxic, biocompatible and
non-pyrogenic; examples of such a material include sugar
derivatives, such as mannitol and dextrose, salts, such as sodium
chloride and potassium chloride, and polyvinylpyrrolidone (PVP).
Portions of U.S. Pat. No. 4,827,940 teaching methods for forming
and applying a mannitol solution are incorporated by reference
herein. According to an alternate embodiment, a covering in the
form of a thin wall tube may be deployed over retaining segment 30
in place of coating 36. It should be noted that any of the
embodiments described herein may include such a coating or a
covering facilitating positioning of lead bodies.
FIG. 2C is an enlarged plan view of means for retention according
to another embodiment. FIG. 2C illustrates a retaining segment 300
coupled to a portion of lead body 312 and including a proximal end
3210 and a plurality of projections 310, each of which extend
around all or a portion of a circumference of lead body 312 and
extend laterally from lead body 312 at angle 33 with terminal ends
311 of projections 310 directed toward proximal end 3210.
FIG. 2D is an enlarged partial section view of means for retention
according to yet another embodiment of the present invention. FIG.
2D illustrates a retaining segment 350 including a plurality of
fish scale-like projections 355 positioned side-by-side about a
circumference of lead body 312 and along a length of segment 350,
and including terminal ends 351 directed toward a proximal end
3215. Projections 355 of figure 2D are shown positioned in an
overlapping pattern, for example, disposed in multiple
circumferential rows and each circumferential row of scales is
disposed in offset relation to an adjacent circumferential row of
scales; FIG. 7B further illustrates a variation in an offset
relation of rows of scales according to another embodiment.
FIG. 2D further illustrates projections 355 as discrete elements
embedded in an underlying surface 375 of segment 350 according to
one embodiment of the present invention. Fish scale-like
projections 355 may be arranged in a manner of actual fish scales
of which there are four main types, each type having numerous
variations; the four main types are: a.) Placoid, b.) Cosmoid, c.)
Ganoid and d.) Cycloid and ctenoid. According to various
embodiments of the present invention, projections 355 may take on
any of forms and be arranged in any of the manners described by
these four main types of actual fish scales.
Retaining segment 350 is characterized in allowing movement of body
312 within a vessel in a first direction to an implanted position
while preventing movement of body 312 from the implanted position
in the opposite direction. Thus, a tendency for lead body 312 to
dislodge from the implanted position in the vessel would be
prevented by terminal ends 351 of fish scale-like projections 355,
which engage a wall of the vessel. Such projections 355 have an
advantage over standard tine structures, which are commonly found
on implantable leads known in the art, in that the lead fixation
achieved by projections 355 is independent of the geometry of the
implant site in the vessel. One may conceptualize the fixation
afforded by projections 355 as "micro-fixation" as opposed to a
"macro-fixation" of conventional tines or a screw. According to
some embodiments of the present invention, this "micro-fixation" is
further enhanced by a curvature formed in body 312, resulting, for
example, in a serpentine shape, which encourages contact of
projections 355 with the vessel wall at the implant site. Methods,
which may be employed to keep body 312 straight during
implantation, include use of a stylet wire within body 312 or a
catheter external to body 312 and are well known to those skilled
in the art. Furthermore according to some embodiments, a coating,
for example coating 36 described in conjunction with FIG. 2B, is
formed over retaining segment 350 to protect projections 355 during
implantation.
FIG. 2D also illustrates, by way of a dashed line connecting
projections 355 around a circumference, another embodiment in which
embedded elements forming projections may be rings or portions of a
coil circling a portion of or the entire circumference of segment
350 creating projections similar to projections 310 illustrated in
FIG. 2C.
According to further alternate embodiments, some or all projections
of a retaining segment, for example projections 385, 31, 310 and
355 (FIGS. 2A-D), each include micro-features further enhancing
engagement of the projections with the vessel wall. In FIG. 2A such
a feature is illustrated on one of projections 385 as a hole or
indentation 25; in FIG. 2B such a feature is illustrated as a
modified surface 26 on one of projections 31 wherein surface 26
includes texture, adhesive spots, or some material promoting
thrombotic adhesion to vessel wall.
Methods for forming various embodiments of retaining segments, for
example those depicted in FIGS. 2A-D, include, but are not limited
to, molding, extrusion, cutting, laser ablation, and coating. These
methods may form projections directly in outer surfaces, such that
they are integral with a bulk material underlying the surfaces, or
may integrate the projections with the surface by embedding or
adhering.
According to some embodiments of the present invention, transfer or
injection molding, using methods known to those skilled in the art,
are used to form a retaining segment including projections,
examples of which include those depicted in FIGS. 2B-C. According
to other embodiments, a cutting process may be used to create
projections on a retaining segment, for example segment 380
illustrated in FIG. 2A; a blade may be used to nick the surface or
to cut all the way through a wall of the retaining segment.
Alternatively, laser ablation may be used to create projections
from a bulk material of a retaining segment, i.e. FIGS. 2B-C, or by
exposing, at a surface of the segment, portions of materials which
have been embedded within the bulk material underlying the surface
during, for example, a molding or extrusion process, i.e. FIG. 2D.
U.S. Pat. No. 5,580,699 describes a suitable laser ablation
process, which may be used to form retaining segments and the
pertinent teachings of the '699 patent are incorporated by
reference herein. U.S. Pat. No. 4,272,577 describes an extrusion
process for forming ski bases having direction-dependent friction
coefficients wherein harder particles, within a plastic matrix
flowing through a slit nozzle, become obliquely oriented relative
to the surface of the base; in one case, by means of a temperature
gradient across the nozzle. We contemplate that similar methods may
be developed by those skilled in the art, according to the
teachings of the '577 patent, in order to extrude retaining
segments according to the present invention, and incorporate by
reference the pertinent teachings of the '577 patent herein. Some
composite materials suitable for embodiments of the present
invention include but are not limited to polyamide and polyimide
particles, polyester fibers, carbon fibers or particles and any
combination thereof blended with silicone.
According to further alternate embodiments a coating applied to a
surface of a retaining segment may form projections and or
micro-features on projections, for example similar to those
illustrated in FIGS. 2B-C. Stewart et al. describe an example of a
suitable coating process via plasma deposition in commonly assigned
U.S. Pat. No. 6,549,811, which is incorporated by reference in its
entirety herein. Furthermore coatings including particles blended
within, for example a silicone medical adhesive including
biocompatible metal particles or hard plastic particles may form an
embodiment of the present invention for example similar to those
illustrated in FIGS. 2B and 2D.
FIG. 3 is a plan view of a lead 40, which may incorporate retention
means according to embodiments of the present invention. FIG. 3
illustrates lead 40 including a proximal portion 43, a first
preformed bend 41 extending from proximal portion 43 to an
intermediate segment 45 and a second preformed bend 42 extending
from intermediate segment 45 to distal segment 46, which is
terminated by a tip 44. Such a lead is fully described in commonly
assigned U.S. Pat. No. 5,999,858, which is herein incorporated by
reference in its entirety. According to embodiments of the present
invention, first and second bends 41 and 42 acting as means for
retention of lead body in a coronary vessel, for example a coronary
sinus 605 or a branch vessel 607 thereof illustrated in FIG. 6, are
supplemented by any of the retaining segments described herein,
which may be formed along the lead body surface at first bend 41,
intermediate segment 45, second bend 42, distal segment 46, or any
combination thereof. Any other combination of bends within a lead
body is within the scope of the present invention, for example that
resulting in a serpentine shape, as previously described.
FIGS. 4A-B are partial plan views of one embodiment of lead 40
showing only a portion at first bend 41, which includes a retaining
segment formed by projections 51. According to some embodiments of
the present invention a retaining segment may be activated by a
bending of a lead body as illustrated in FIGS. 4A-B. If a stylet,
for example stylet 18 shown in FIG. 1, is inserted into lead 40 to
straighten preformed bend 41, projections 51 become approximately
parallel with an outer surface of lead 40, as illustrated in FIG.
4A. Once the stylet is removed preformed bend 41 reforms such that
projections 51 protrude laterally and are thus activated to prevent
rearward motion of lead 40 within a vessel. If it becomes necessary
to reposition lead 40, the stylet may be reinserted to straighten
bend 41 thus bringing projections into approximate alignment with
the surface of lead 40. It should be noted that the embodiment
illustrated in FIG. 2D may be of the type illustrated in FIGS.
4A-B.
FIG. 3 further illustrates lead 40 including an anchoring sleeve 48
positioned about proximal portion 43 thereof. According to an
additional embodiment of the present invention, means for retention
as illustrated herein, may be formed along an outer surface of
proximal portion to provide frictional forces complementing
anchoring sleeve 48 at a venous entry point. The means for
retention may either engage an inner surface of anchoring sleeve 48
or engage a vein wall in proximity to the entry point.
FIGS. 5A-B schematic views of a portion of a lead body including
retention means according to yet another embodiment. FIGS. 5A-B
illustrate a lead body 20 including a plurality of hair-like
projections or fibers 205 each attached at one end to lead body 20
and directed by their attachment points 23 to extend out from and
along a length of body 20 toward a proximal end 221 of body 20.
According to the illustrated embodiment, as lead body 20 is
advanced distally in a vessel 207 per arrow A, as in FIG. 5A,
projections 205 are suspended proximally; when lead body 20 is
retracted proximally per arrow B, as in FIG. 5B, projections 205
are forced toward a distal end 222 of body 20 to become bunched up
and wedged between body 20 and a wall of vessel 207, thereby
providing retention means for lead body 20. Projections may be
formed from a bioabsorbable polymer, for example polyglyocolic acid
or polylactic acid. Alternately projections 205 may be formed from
polyester fibers or some other material promoting thrombotic
adhesion with the vessel wall to enhance retention within vessel
207; such thrombotic projections may include a non-thrombogenic
coating adapted to dissolve after the lead is positioned per FIG.
5B, examples of which include a benzalkonium chloride-heparin
solution and polyvinylpyrrolidone. Projections 205 may be attached
at attachment points 23 by embedment within lead body 20 or by
adhesive attachment, for example by means of silicone medical
adhesive.
FIG. 6 is a schematic view of an exemplary medical device, which
may incorporate retention means according to embodiments of the
present invention. FIG. 6 illustrates the medical device including
a therapy generator 600 coupled to a lead 60 implanted within
branch vessel 607 emanating from coronary sinus 605. Lead 60
including a connector terminating a proximal portion 62, an
electrode in proximity to a distal end 66 and a conductor extending
through an outer insulative sheath (similar to lead 10 illustrated
in FIG. 1) may deliver electrical therapy, or may deliver infusions
of therapeutic fluids from generator 600 through a central lumen.
FIG. 6 further illustrates potential retention segment sites 65,
61, and 63 along lead 60 where projections of retention segments
according to embodiments of the present invention would engage a
wall of vessels 605 and 607 to prevent rearward dislodgment of lead
60 from vessel 607.
FIG. 7A-B are plan views of lead distal portions including
retention means according to additional embodiments of the present
invention, which incorporate dual retaining segments. FIG. 7A
illustrates a lead body 71 including retaining segment 380,
previously illustrated in FIG. 2A, and a second retaining segment
780 having projections extending in a generally opposite direction
to those of segment 380; likewise FIG. 7B illustrates a lead body
72 including a retaining segment 750, including scale-like
projections similar to that previously illustrated in FIG. 2D, and
a second retaining segment 755 having projections extending in a
generally opposite direction to those of segment 750. According to
the illustrated embodiments, once lead bodies 71, 72 are positioned
in a vessel for therapy delivery, the dual retaining segments
prevent both further forward motion and rearward motion. FIGS. 7A-B
further illustrate a tubular structure 700, which would be
positioned over retaining segments 380 and 780 and 750 and 755, per
arrow C, in order to shield the retaining segments during the
positioning of lead bodies 71, 72; such a tubular structure may be
a delivery or guiding catheter, examples of which are well known to
those skilled in the art. According to an alternate embodiment a
soluble coating, illustrated by dashed lines, as previously
described in conjunction with FIG. 2B, temporarily covers retaining
segments 380 and 780 and 750 and 755 during positioning of lead
bodies 71, 72. It should be noted that further alternate
embodiments of the present invention include any type of retaining
segments having directional projections, similar to those
illustrated in FIGS. 2A and 2D, formed as dual retaining segments
as illustrated in FIGS. 7A-B.
Although embodiments of the present invention are described in the
context of therapy delivery, diagnostic devices adapted for
insertion within a blood vessel may also incorporate retention
means described herein and thus fall within the scope of the
present invention. In the foregoing detailed description, the
invention has been described with reference to specific
embodiments. However, it may be appreciated that various
modifications and changes can be made without departing from the
scope of the invention of the appended claims.
* * * * *